Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins, and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life saving. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys.
Hemodialysis and peritoneal dialysis are two types of dialysis commonly used to treat loss of kidney function. Hemodialysis treatment utilizes the patient's blood to remove waste, toxins, and excess water from the patient. The patient is connected to a hemodialysis machine and the patient's blood is pumped through the machine. Catheters are inserted into the patient's veins and arteries to connect the bloodflow to and from the hemodialysis machine. The waste, toxins, and excess water are removed from the patient's blood and the blood is infused back into the patient. Hemodialysis treatment lasts several hours and is generally performed in a treatment center about three or four times per week.
Peritoneal dialysis utilizes a dialysis solution and dialysate, which is infused into a patient's peritoneal cavity. The dialysate contacts the patient's peritoneal membrane in the peritoneal cavity. Waste, toxins, and excess water pass from the patient's bloodstream through the peritoneal membrane and into the dialysate. The transfer of waste, toxins, and water from the bloodstream into the dialysate occurs due to diffusion and osmosis. The spent dialysate is drained from the patient's peritoneal cavity to remove the waste, toxins, and water from the patient and replaced.
Peritoneal dialysis catheters are used to transfer the fresh dialysate into the peritoneal cavity and remove spent dialysate from the cavity. Typically, a peritoneal catheter is implanted into the peritoneal cavity and remains implanted for an extended period of time. For example, the average catheter may remain implanted for about 18–24 months, but it is not unusual for a catheter to remain indwell for more than 2 years.
There are various types of peritoneal dialysis, including continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis. CAPD is a manual dialysis treatment in which the patient connects the implanted catheter to a drain and allows spent dialysate fluid to drain from the peritoneal cavity. The patient then connects to a bag of fresh dialysate and manually infuses the fresh dialysate through the catheter and into the patient's peritoneal cavity. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the cavity to transfer waste, toxins, and excess water from the patient's bloodstream to the dialysate solution. After the dwell period, the patient repeats the manual dialysis procedure. The patient performs several drain, fill, and dwell cycles during the day, for example, about four times per day. Each treatment cycle typically takes about 3–4 hours. Manual peritoneal dialysis performed by the patient requires quite a lot of time and effort by the patient. The patient is routinely inconvenienced leaving ample opportunity for therapy enhancements to improve patient quality of life.
Automated peritoneal dialysis is similar to continuous peritoneal dialysis in that the dialysis treatment includes a drain, fill, and dwell cycle. However, a dialysis machine automatically performs 3–4 cycles of peritoneal dialysis treatment, typically overnight while the patient sleeps. A dialysis machine is fluidly connected to the implanted catheter. The dialysis machine is also fluidly connected to a source of fresh dialysate, such as a bag of dialysate solution, and to a fluid drain. The dialysis machine pumps spent dialysate from the peritoneal cavity through the catheter to the drain. Then, the dialysis machine pumps fresh dialysate from the dialysate source through the catheter and into the patient's peritoneal cavity. The dialysis machine allows the dialysate to dwell within the cavity to transfer waste, toxins, and excess water from the patient's bloodstream to the dialysate solution. The dialysis machine is computer controlled so that the dialysis treatment occurs automatically when the patient is connected to the dialysis machine, for example, overnight. Several drain, fill, and dwell cycles will occur during the treatment. Also, a last fill is typically used at the end of the automated dialysis treatment so that the patient can disconnect from the dialysis machine and continue daily functions while dialysate remains in the peritoneal cavity. Automated peritoneal dialysis frees the patient from manually performing the drain, dwell, and fill steps, and can improve the patient's dialysis treatment and quality of life.
Various catheters exist for patient implantation to perform peritoneal dialysis. Existing peritoneal catheters include single lumen and dual lumen catheters. A single lumen catheter has a single fluid passageway through the catheter, and a dual lumen catheter has two fluid passageways. Single lumen catheters allow fluid flow in only one direction into or out of the patient at any given moment. Dual lumen catheters allow fluid flow both into and out of the patient at the same time. Because catheters are surgically implanted into patients and because the catheters allow fluids to be infused into and drained from the patients, improvements to catheters and methods of implanting and using catheters can be beneficial.